T-shirts on sale at the TUC conference in Brighton that suggest union members will dance on Margaret Thatcher's grave have been described as "tasteless and totally inappropriate" by the TUC general secretary, Brendan Barber.

The T-shirts, which are raising funds for the Derbyshire Unemployed Workers Centre (DUWC), are being sold outside the main hall at the Brighton Centre and have been condemned by Conservative MPs.

The garment is emblazoned with a tombstone on which "Thatcher" is etched, with the slogan below reading "A generation of trade unionists will dance on Thatcher's grave." Barber said the T-shirts were "tasteless and totally inappropriate".

The reaction among delegates was mixed. One delegate rejected criticism from the Conservative MP Priti Patel, who said she was "appalled". The delegate said: "I am not particularly appalled. She [Thatcher] had much worse from Spitting Image."

Another added that accusations of insensitivity should be levelled at the Conservative party for its policies during the Thatcher era. "The trade union movement thinks that Thatcher was insensitive to communities, our industries."

Colin Hampton, the DUWC co-ordinator running the stall, said he had sold around 20 T-shirts during the conference. He said the merchandise had been inspired by the debate over whether the former prime minister should be given a state funeral.

"I don't think it is rejoicing in the death of Thatcher. It's about the feeling that she will be praised to the hilt when she dies, having ruined so many lives." Hampton added that the DUWC also worked with former miners whose livelihoods were devastated in the 1980s.

Dai Hudd, the deputy general secretary of Prospect, the professionals' union, said that calling on people to dance on Thatcher's grave was "nonsense" and "infantile" but there was anger over her government's legacy. "That era made us a nastier nation," he said, adding: "She might get her own back and be buried at sea."